Conventionally, the semiconductor process involves the process of depositing an insulating film or conducting film over a semiconductor substrate and the process of patterning the insulating or conducting film through etching, those processes being performed repeatedly to form a semiconductor circuit.
The deposition and etching of a film utilize chemical or physical reactions; thus, the deposition and etch rates depend on the temperature of a semiconductor substrate (substrate temperature). The quality of the deposited film also varies with the substrate temperature. Therefore, in order to perform film deposition and etching with good repeatability, it is essential to control the substrate temperature during deposition and etching.
Conventionally, a semiconductor substrate is often heated by irradiating it with infrared radiation from its top or back. In many cases, films have been formed in advance over the semiconductor substrate to be heated. The efficiency of absorbing infrared radiation varies with the types of films.
For this reason, the semiconductor substrate heating method using an infrared lamp suffers from a problem that it is impossible to control the substrate temperature accurately because the infrared radiation absorbing efficiency varies with the types of films. The method has another problem that the substrate temperature elevates greatly during infrared ray irradiation because the semiconductor substrate can not be cooled during that time.
Recently, a method has been often used by which a hot plate having a resistance heating element incorporated is fixed to a stage equipped with a cooling means, a semiconductor substrate placed on the hot plate is heated by the heating element, and the semiconductor substrate is cooled by means of the cooling means so that the substrate temperature may not rise greatly.
There are some methods of fixing a semiconductor substrate to the hot plate: exhausting the hot plate from its back, using electrostatic absorption, etc. However, the back exhausting method has a problem of its inability to be used in a vacuum.
In contrast, the electrostatic absorption method has come into frequent use in recent years because the semiconductor substrate can be fixed to the hot plate with no contact with its surface into which the device is manufactured and use can be made even in a vacuum.
With the hot plate using such an electrostatic chuck, the substrate temperature is measured by inserting a thermocouple 81 into a hole formed in the back of a hot plate 80 and measuring an electromotive force developed by the thermocouple as shown in FIG. 6. In this figure, 82 denotes an electrostatic chuck electrode and 83 denotes a heating electrode.
It is an object of the present invention to provide a hot plate which permits the substrate temperature to be measured with good repeatability.
It is another object of the present invention to provide a method of manufacturing a semiconductor device which permits the prevention of variations in processing of the semiconductor substrate due to variations in measured temperatures of the hot plate.
A hot plate of the present invention is characterized by comprising: a plate body on which a semiconductor substrate is placed; an heating electrode formed within the plate body; and at least one temperature measuring probe formed within the plate body.
A method of manufacturing a semiconductor device of the present invention is characterized by comprising the steps of: placing a semiconductor substrate on a hot plate including a plate body on which a semiconductor substrate is to be placed, a heating electrode formed within the plate body, and a temperature measuring probe formed within the plate body (in this case, it is preferable to fix the substrate to the hot plate through the use of an electrostatic chuck); and processing the semiconductor substrate while maintaining the semiconductor substrate at a predetermined temperature by controlling a voltage application unit for applying a voltage to the heating electrode and a cooling unit for cooling the hot plate on the basis of temperature measurements by the temperature measuring probe.
In the present invention, the temperature measuring probe is formed within the plate body. Because this type of temperature measuring probe can be formed with good reproducibility, the temperature of the hot plate can be measured with good repeatability by measuring the temperature of the probe.
By using the hot plate of the present invention as a hot plate, the temperature of the semiconductor substrate can be measured with good repeatability, which permits the prevention of occurrence of variations in a semiconductor substrate process such as film formation.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.